Flat or low-sloped roofs are often covered with polymeric membranes. Common among the membranes that have the mechanical properties needed to be technologically useful are thermoset membranes prepared with EPDM rubber, or thermoplastic membranes prepared with ethylene-propylene reactor copolymers or blends of polyethylene and polypropylene. These membranes typically contain carbon black and/or mineral fillers, which provide advantageous mechanical properties to the membranes.
Many roofs, especially flat or low-sloped roofs, are covered with a polymeric membrane. Polymeric membranes used in these applications include both thermoset membranes and thermoplastic membranes. Exemplary thermoset membranes include EPDM rubber. Thermoplastic membranes include PVC membranes and olefinic-based thermoplastic membranes. Olefinic-Based thermoplastic membranes offer unique advantages, including the ability to extrude the membrane, which facilitates manufacturing, and the ability to heat weld the membranes to form a continuous water barrier on the roofing surface.
Because the olefinic-based membranes are rich in hydrocarbon content, they may require significant flame retardants to pass industry and governmental flame and/or fire standards. The use of these flame retardants can have some drawbacks including cost and loss of mechanical properties.